This invention relates to an automatic locking apparatus for a movable module in a device and more particularly to an automatic locking apparatus that employs the gravitational weight of the device itself as the action force for locking or releasing the movable module in the device.
In many devices such as a scanner and other similar optical devices, there is usually a movable module for performing scanning, image recognition or other optical and sensing function. These movable modules are usually driven reciprocally within a selected displacement by a particular transmission means such as a belt, a gear rack and the like when in use. When not in use, the movable module is usually set to return to an initial position.
However, due to some reasons such as driving power limitation, weight of the movable module or design deficiency of the transmission means, the movable module might not always have an automatic locking design. In the case that the device does not include an automatic locking device for anchoring the movable module while not in usage, the device might have a substantial high possibility, while moving the device, that the movable module might slip away from its initial position and hit other components in the device. It is obvious that any collision happens to the movable device might lead to some damages, and such damages are definitely unwelcome.
In order to prevent aforesaid problem, there are prior arts to use manual locking means to anchor the movable module at a fixed selected location in the device. U.S. Pat. Nos. 5,769,515 and 5,973,866 are two of these efforts.
Generally, aforesaid prior arts may be well used for a planned movement of the device. However, there are unplanned occasions that the device will be moved incidentally and a non-lock setting might be met due to people""s negligence. Under such abnormal situations, the movable module may remain at a unlocking or free-to-slip position, and could result in damage of the device.
It is an object of this invention to provide an automatic locking apparatus for a movable module in a device that utilizes the location and the gravitational weight of the device to trigger a control means for locking or releasing the movable module.
It is another object of this invention to provide an automatic locking apparatus that will automatically lock a movable module at an initial position when the device is moved away from a resting place and will automatically unlock the movable module when the device is placed on a working location.
In one aspect of the present invention, the device has a bottom wall for resting on a support plane, and the movable module is movable inside the device. The automatic locking apparatus includes an input unit, a transfer unit and an output unit.
The input unit is located on the bottom wall for detecting if the device is posed at a normal state (i.e. resting on the support plane) or an abnormal state (i.e. not being positioned on the support plane).
The transfer unit is located in the device to receive input from the input unit and to trigger an output action.
The output unit is actuated by the transfer unit to lock or release the movable module according to a preset condition. Generally, the movable module will be released under a normal state and locked under an abnormal state.
In one embodiment of this invention, the input unit is a sensor located under the bottom wall. The transfer unit is an electric controller. The output unit is an actuator (such as a solenoid) which has a pin movable to lock or release the movable module. The sensor may have a probe pin to trigger the pin to perform locking or releasing action. This embodiment may include an independent power supply for the apparatus to function normally even when the external power supply is absent.
In another embodiment of the present invention, the transfer unit may include a slide bar and a spring mounted in the bottom wall. The slide bar has a lower end for serving as an input unit passing through the bottom wall to contact the support plane and a lock stub at an upper end for serving as an output unit for locking or releasing the movable module. The spring will trigger the movement of the slide bar for locking or releasing action under an abnormal or a normal condition. The slide bar thereof has a lower limit hook and an upper limit shoulder for limiting the movement of the slide bar within a selected displacement range.
In yet another embodiment of the present invention, the input unit may include an input bar passing through the bottom wall and engaged with a spring held in the bottom wall. The output unit may include an output bar having a free end to form a locking hook. The transfer unit may include a pivotal means to couple the input bar and the output bar, and a lever means for triggering the output bar to lock the movable module under abnormal conditions, or to release the movable module under normal conditions.
In another aspect of the present invention, the locking hook may be replaced by a magnet to mate and attract another magnet located in the movable module under a locking state.